1. Field of the Invention
The present invention relates to a heat-resistant air hose for a diesel engine for use as a diesel particulate filter (DPF) sensor hose; and a vacuum brake hose, an air hose, a turbo (supercharger) air hose and the like for a diesel engine.
2. Description of the Art
From the viewpoint of worldwide increasing environmental consciousness, DPF system and turbo system for decreasing PM (Particulate Matter) and NOx in the exhaust gas have been steadily adopted. As a fuel hose and an air hose, conventionally used, for example, a hose such that an inner layer in contact with fuel is formed by fluororubber or acrylic rubber is proposed (see, for example, Japanese unexamined Patent Publication Nos. H07-229584 and 2003-82029).
At the same time, control of exhaust emissions from diesel-powered vehicles has been recently tightened. New engine system (common-rail injection system) corresponding to such tightened control, and DPF system and turbo system for decreasing PM and NOx in the exhaust gas have been steadily adopted. Under such circumstances, there have been increasing demands on requirements for the heat-resistant air hoses for a diesel engine, such as a DPF sensor hose. In other words, the temperatures of the DPF system and the turbo system are elevated in order that combustion efficiency is improved to decrease exhaust gas such as PM and NOx. Thus, higher heat resistance is required for the heat-resistant air hose for a diesel engine as compared with a conventional hose. However, a conventional hose using fluororubber (FKM) for an inner layer includes an acid receiver, exhaust-gas resistance (acid resistance) is inferior, while a conventional hose using an epichlorohydrin-ethylene oxide copolymer (ECO) for an outer layer has insufficient heat-resistance.
In view of the foregoing, it is an object of the present invention to provide a heat-resistant air hose for a diesel engine excellent in exhaust-gas resistance (acid resistance), heat resistance and flame retardance.